Signal processing system for inertial sensor

1. An acceleration sensing system, comprising: a dither assembly; a plurality of accelerometers mounted to the dither assembly for producing signals that indicate acceleration for three mutually perpendicular axes; apparatus for applying a dither drive signal to the dither assembly such that the accelerometers are dithered at a frequency .omega..sub.D and produce electrical accelerometer output signals that are modulated at the frequency .omega..sub.D ; apparatus for producing a first reference signal that is in phase with the dither drive signal and a second reference signal that is in quadrature with the dither drive signal; an accelerometer signal pickoff arranged to provide the accelerometer output signals; a multiplexer connected to the accelerometer signal pickoff; sensor signal processing apparatus connected to the multiplexer for sequentially processing sensor output signals for each of the three axes, the sensor signal processing apparatus including: a first rebalance path that includes: an in-phase demodulator arranged for demodulating the sensor output signal with the first reference signal; a first servo compensator connected for processing signals output from the in-phase demodulator to provide a rate signal; and an in-phase remodulator connected to the first servo compensator to remodulate the rate signal with the first reference signal; a second rebalance path that includes: a quadrature-phase demodulator arranged for demodulating the sensor output signal with the second reference signal; a second servo compensator connected for processing signals output from the in-phase demodulator to provide a signal indicative of the Coriolis acceleration of the sensor; and a quadrature-phase remodulator connected to the second servo compensator to remodulate the rate signal with the second reference signal; an acceleration channel that includes an acceleration channel servo compensator arranged to produce an acceleration feedback signal that is indicative of the linear acceleration input to the sensor along selected input axes; and an arithmetic logic unit connected to receive signals output from the first and second rebalance paths and the acceleration channel and produce an acceleration feedback signal; and apparatus for applying the acceleration feedback signal to the accelerometers to suppress motion of the accelerometers from Coriolis acceleration.

2. The apparatus of claim 1 wherein the apparatus for applying the dither drive signal to the dither assembly comprises: a processing unit that includes a look-up table for providing the first and second reference signals as being proportional to cos(.omega..sub.D t) and sin(.omega..sub.D t), respectively; a cosine modulator arranged to receive the first reference signal; a sine modulator arranged to receive the second reference signal; a summer arranged to receive signals output from the cosine and sine modulators and produce a summer output having a specified amplitude and phase; and apparatus for applying the summer output to the accelerometers to dither the accelerometers.

3. The apparatus of claim 2, further including apparatus for adjusting the dither angular velocity to be in-phase with the cosine waveform output of the look-up table.